As mobile telecommunications demands continue to increase, a number of different frequency bands have been allocated for mobile telecommunications in various geographical regions.
FIG. 1 is an example table 100 of mobile telecommunications bands for the evolved UMTS Terrestrial Radio Access Network (E-UTRA) from the 3rd Generation Partnership Project (3 GPP). Table 100 shows a plurality of communication bands 110, each communication band including a so-called “up-link” frequency band 120 on which a mobile telecommunication device transmits and a corresponding so-called “down-link” frequency band 130 on which a mobile telecommunication device receives. Hereinafter, “up-link” frequency bands 120 will be referred to as transmit bands 120, and “down-link” frequency bands 130 will be referred to as receive bands 130.
As shown in Table 100, the communication bands 110 span an RF/microwave frequency range of about 700 MHz to 2700 MHz. Associated with each communication band 110 is a corresponding duplex mode 140 for operation, either frequency division duplexing (FDD) or time division duplexing (TDD). It can be seen from FIG. 1 that when a communication band 110 employs FDD operation, then there is a frequency offset between the corresponding transmit band 120 and the corresponding receive band 130, and when a communication band 110 employs TDD operation, then the corresponding transmit band 120 and the corresponding receive band 130 have the same frequency range as each other.
It will be noted that in some cases the transmit bands 120 and/or receive bands 130 of two or more of the communication bands 110 have overlapping frequencies. In general, communication bands 110 with overlapping frequencies are utilized in different geographical regions (e.g., U.S., Europe, Asia, etc.).
Meanwhile, there has been a desire to support non-simultaneous operation in many different communication bands 110 so that one mobile telecommunication device can be used with many different mobile telecommunication systems operating in different communication bands 110, and in some cases in different geographical regions as a user travels from place to place.
FIG. 2 illustrates one example of an arrangement 200 for a transceiver front-end for a mobile telecommunication device that supports non-simultaneous operation in a plurality of different communication bands. Arrangement 200 includes a transmit/received (T/R) and band switch 210, a plurality of duplexers 220-i (here, i (1,6)), and a power amplifier (PA) module 230.
T/R and band switch 210 has a common port 213 connected to an antenna 10, and a plurality of switched ports 215-j (here, j (1,8)) that are selectively coupled to common port 213 under control of a mobile telecommunication device in which arrangement 200 is provided. As shown in FIG. 2, six of the switched ports 215-j are connected to corresponding duplexers 220-i, and two of the switched ports 215-j for GSM Hi bands (1800, 1900 MHz) transmit signal 235 and GSM Lo bands (850, 950) transmit signal 245 are connected to PA module 213.
In general, switches can be divided into two categories: (1) mechanical or electromechanical switches; and electronic switches, including solid state switches. Mechanical or electromechanical switches operate to make or break an electrical connection by connecting and disconnecting a physical contact between two terminals. Examples of mechanical switches include toggle switches, push-button switches, mercury switches, and knife switches. Examples of electromechanical switches include electromagnetic relays, reed switches, and RF microelectromechanical system (MEMS) switches. Examples of electronic switches include diodes, triacs, silicon-controlled rectifiers, transistors (e.g., field effect transistors), and logic gates. In general, electronic switches can operate faster (i.e., higher switching speeds) or with a longer lifetime (i.e., a greater number of switching cycles) compared to mechanical or electromechanical switches. On the other hand, in many applications, and particularly at RF and microwave frequencies, mechanical or electromechanical switches can provide significantly lower insertion losses when the switch is “ON” and greater electrical isolation when the switch is “OFF” than be achieved with electronic switches.
In arrangement 200, T/R and band switch 210 is required to switch very rapidly and repeatedly between transmit and receive switched ports 215-j to support TDD operation, and therefore must be capable of millions of rapid state changes. Accordingly, an electronic switch is used for T/R and band switch 210.
In general, a duplexer is a device that allows bi-directional (duplex) communication over a single communication band at the same time. In arrangement 200, each duplexer 220-i supports a corresponding communication band 110 and includes two filters (e.g., bandpass filters) 222: a transmit filter 222 for the corresponding transmit band 120 and a receive filter for the corresponding receive band 130. Each duplexer 220-i has a common port 223, a transmit port 225, and a receive port 227. Each common port 223 is connected to a corresponding switched port 215-j of T/R+band switch 210. Each transmit port 225 is connected to PA module 230, and each receive port 227 is connected to a receiver circuit for the mobile telecommunication device (not shown in FIG. 2).
Functionally, in the arrangement 200 each switched port 215-j of T/R and band switch 210 supports a different communication band (or part of a different communication band), and only one communication band can be used at a time. Connecting to two or more switched ports 215-j at the same time would cause the circuits attached to each switched port 215-j to unacceptably load one another. Also arrangement 200 can support both TDD and FDD operation, both of which are typically required in many mobile telecommunication devices. Since TDD operation requires T/R and band switch 210 to toggle between transmit and receive states very rapidly and frequently, as noted above this limits the technology that can be used to implement T/R and band switch 210, and this typically results in a significant insertion loss. Since a primary contributor to loss is leakage into open throws, adding throws to T/R and band switch 210 further increases the loss.
Increases in data traffic have created an interest in improved bandwidths. As one way to support higher data throughput, recent releases of the 3 GPP Specification have started to include the potential for multi-carrier use for Radio Access Networks (RANs).
FIG. 3 illustrates provisions for multicarrier operation by a mobile telecommunication device as provided in Release 8, Release 9, and planned future releases of the 3 GPP Specification. As shown in FIG. 3, Release 8 provides for multi-carrier reception by a mobile telecommunication device, but only for carriers or channels within a single communication band. Release 9 provides for simultaneous multi-carrier reception by a mobile telecommunication device of signals with carriers or channels in two or more different communication bands. Planned future releases are expected to provide for simultaneous transmission and reception by a mobile telecommunication device with carriers or channels in two or more different communication bands.
As shown in FIG. 2, arrangement 200 can support multi-carrier or multi-channel reception within a single communication band as provided in Release 8 of the 3 GPP Specification. However, simultaneous multi-band communication as provided in Releases 9 and planned for future releases of the 3 GPP Specification is not possible with arrangement 200.
FIG. 4 illustrates another example of an arrangement 400 for a transceiver front-end for a mobile telecommunication device. Arrangement 400 includes two T/R and band switches 210-1 and 210-2, each connected to a corresponding antenna 20-1 and 20-2. In particular, antenna 20-1 is a hi-band or high frequency antenna handing signals in a frequency range of 1700-2200 MHz, and antenna 20-2 is a low-band or low frequency antenna handing signals in a frequency range of 800-1000 MHz.
In the arrangement 400, some simultaneous operation in different communication bands can be supported, as long as the different communication bands are connected to separate antennas. In arrangement 400, one high frequency communication band and one low frequency communication band could be operated at the same time via the separate hi-band antenna 20-1 and low-band antenna 20-2.
However in arrangement 400 the number of bands available for simultaneous communication cannot exceed the number of antennas. Furthermore, there is a fundamental limitation on the flexibility of selecting which communication bands can be operated at the same time. That is, only pairs of communication bands that are connected to different antennas can be utilized at the same time.
What is needed, therefore, is an arrangement for a front end of a mobile telecommunications device that can allow for simultaneous multi-band communication without requiring separate antennas for each simultaneously-operated communication band.
In an example embodiment, an apparatus comprises: a first multiplexer configured to allow bi-directional communication over a first plurality of multiplexed communication bands that each include a corresponding transmit band and a corresponding receive band, wherein none of the transmit bands of the first multiplexer have transmit frequencies that overlap with any receive frequencies of any of the receive bands of the first multiplexer; a second multiplexer configured to allow bi-directional communication over a second plurality of multiplexed communication bands that each include a corresponding transmit band and a corresponding receive band, wherein none of the transmit bands of the second multiplexer have transmit frequencies that overlap with any receive frequencies of any of the receive bands of the second multiplexer; and an electromechanical band switch configured to selectively connect the first and second multiplexers to a common antenna.
In another example embodiment, a method comprises: multiplexing to a first common port a first plurality of communication bands each supporting a corresponding bi-directional communication signal that includes a corresponding transmit signal that is transmitted in a corresponding transmit band and a corresponding receive signal that is received in a corresponding receive band; multiplexing to a second common port a second plurality of communication bands each supporting a corresponding bi-directional communication signal that includes a corresponding transmit signal that is transmitted in a corresponding transmit band and a corresponding receive signal that is received in a corresponding receive band; and selectively connecting one of the first common port and the second common port to an antenna.
In yet another example embodiment, an apparatus comprises: one or more receivers; one or more transmit amplifiers; a first multiplexer having a common port, a plurality of transmit ports connected to the one or more transmit amplifiers, and a plurality of receive ports connected to the one or more receivers; a second multiplexer having a common port, a plurality of transmit ports connected to the one or more transmit amplifiers, and a plurality of receive ports connected to the one or more receivers; and an electromechanical band switch configured to selectively connect the first and second multiplexers to an antenna.